Boundary Butte is perhaps the nicest summit in North Dakota from the perspective of hiking and peakbagging. It is the most prominent peak in the state, the most isolated peak in the state (over 100 miles from higher ground), a pleasant hike through forest, and located directly on the international border and its interesting linear clear-cut.

As near as I can tell, the exact summit of Boundary Butte is at the US-Canada border monument, just a few feet south of the magic 49th parallel (where the WGS84 datum puts it, anyway).